Regulating electric motors.



No. 766,325. PATENTED AUG. 2, 1904.

F. E. CASE.

REGULATING ELECTRIC MOTORS.

APPLICATION FILED APR. 15, 1898.

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No. 766,325. PATENTED AUG. 2, 1904. P. E. CASE.

REGULATING ELECTRIC MOTORS.

APPLICATION FILED APB.,16,1898.

N0 MODEL. 2 SHEETS-SHEET 2.

Patented August 2, 1904:.

UNITE STATES PATENT @FFICE.

FRANK, E. CASE, OF SCHENIHYTADY, NEW YORK, ASSIGNOR TO THE GFNERAL ELEG"R1U COUPANY, A ("ORPORAllON OF NE\V YORK.

REGULATING ELECTRIC MOTORS- SPECIFICATION forming part of Letters Patent N 0. 766,325, dated August 2, 1904:.

Application filed April 15, 1898.

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Be it known that I, FRANK E. (Jase. a citizen of the United States, residing at Schenectady. in the county of Schenectady, State of New York, have invented certain new and useful Improvementsin Regulating Electric Motors, of which the following is a specification.

My invention relates to the regulation of electric motors, particularly to those used on electric railways, and has for its object to provide means for increasing the etliciency of the system by utilizing, in part at least, the energy which ordinarily is wasted in the starting or running resistances. To attain this object, I substitute for a part of the regulating resistance a suitable motive device which by its resistance, self-induction, and counter electromotive force will reduce the current liowing to the main motors, but which instead of wasting energy may accomplish some useful auxiliary purpose, such as storing energy, as by running an air or similar fluid compressor, for instance, for operating the brakes. lam also able by my improvements to positively release the brakes at starting and to accomplish other useful results.

The invention is illustrated in the accompanying drawings.

Figure l is a diagram of circuits of a suitable controller. Fig. 2 is an illustration in diagram of the device used for releasing brakes. Figs. 3 and 4C are a horizontal section and an end elevation, partly in section, respectively, of the device shown in Fig. 2.

In Fig. 1 I have illustrated a well-known form of controller, known in the art as the K controller and described in one of its forms in the patent to \V. B. .Potter, No. 52%,396. It is immaterial what form of controller is used; but this is one well adapted to the invention. The contacts are numbered 1 to 11, respectively, and the contact-plates are correspondingly designated from 1 to 11. The reversing-switch is shown on the right, its contacts being numbered from 12 to 19 and the contact-plates correspondingly numbered, as above described. The various circuits will not be traced, as they will be apparent to those skilled in the art, and the particular combinations are not essential to the invention.

Serial No. 677,645. (No model.)

The general operation of the controller is to couple the motors in series with a resistance in its lirst position and to gradually out the resistance out in subsequent positions until when the contacts 8 to 11 make contact, respectively, with the contact-plates 8 to 11 a shunt is thrown around the second motor with part of the resistance included in series. The shunt is broken as the contacts 8 9 pass oif their contactplates, and the motors are thrown in multiple with full resistance as contacts 7 S touch the plates T" 8". Further rotation of the controller again cuts out resistance. The reversing-switch shown simply acts to reverse the connections between armatures and fields, and need not be more particularly described.

The circuit in the first controller position is as follows: from trolley T to contact 1, contact 2, through the resistance R to the motor M, (to be presently referred to,) through the reversing-switch to contact 18, through armature A, through the reversing-switch to contact 16, through lield F back to the controller-contact 9, contact 8, through the reversing-switch to contact 1%, through armaturc A through the reversing-switch to contact 12, and through lield I to ground at (ir. Thus it will be seen that the small motor M is included in series with the resistance R and, in effect, forms a step of the resistance. To operate to the best advantage, this motor should be one of comparatively high ohmic resistance, so that practically it will act as a dead resistance in the circuit and cut down the current even before it gets up its counter electromotive force. I have illustrated the motor M as geared to a compressor C and pumping air into a reservoir R. It will be manifest thus that whatever cnergv is consumed by the motor will be, so far as the motor eflicieucy permits, stored in the tank R and not simply wasted in heat, as in the ordinary resistances. The compressed air may, particularly when the motor to be regulated is placed upon a railway car or train, be utilized for braking purposes. I have illustrated at R the air-brake mechanism, which may be of any preferred type, acting upon the brake-rods Q. It is further manifest that the principle just indicated might be carried out to a considerable extent by the duplication of motors of the class designated. This I have thought unnecessary to illustrate or describe because it would be readily understood by engineers.

In Figs. 2, 3, and 4 I show another device for accomplishing in another way the same useful results. In this figurelis the car-wheel, and P is the brake-shoe mounted thereon, controlled by the brake-rod Q. This brakerod is attached to an eye D formed in the end of the core or shaft D. This connection is shown as made through a lever Q and a floating linkage, as usual, so that a movement of the core or shaft D to the right will apply the brakes at both ends of the car and a corresponding movement to the left will release them. The details of this linkage, which is similar to that shown in Fig. 1, are well known in the art and need not be illustrated. The spring D is so placed on the shaft as to tend always to set the brakes powerfully on the wheels by moving the core D to the right in Fig. 3.

Mounted upon the same base A with the inclosing shell is a metal piece B, preferably of soft iron, inclosing a solenoid B, which when energized tends to draw the core to the left. It thus appears that when current flows through the solenoid-coil the brakes are released, while at other times the spring tends to cause them to engage the wheels. A stop d and bushing (Z are provided, as shown.

Fastened to one end of the core or shaft D, or integral therewith, is a wedge D which slides between two stops if it. These stops are pierced with an opening in which screwthreads are cut and are mounted on the shaft H, provided with reversely-cut threads h 7L2. This construction is well shown in Fig. 4. The arm F, mounted on the shaft H, is connected to a spring K, which tends always to rotate it in a right-handed direction, and is further connected, through the link L and bell-crank lever M, to a stud 0, preferably placed upon the front platform of the car.

The electrical connections need not be shown in detail, since the coil B simply takes the place of the motor M in Fig. 1 or is in some other way interposed in place of a resistancestop; but this coil should preferably be so placed that it is energized the moment the controller is thrown to such a position as to start the car in either direction.

Assume now that the parts are in the position shown in Fig. 3. The car is assumed to be running and current is flowing through the solenoid B. If now the motors be speeded up by cutting out all the resistance, it is evident that the solenoid will be deenergized. This would tend to set the brakes; but this action is prevented by the wedge D and the stops k /2.*, which bear upon it, since it is obvious that in order to set the brakes it is necessary that the stops ]L3 if be separated, which would involve a partial rotation of the arm F brakes.

necessary.

against the spring K. The parts will therefore remain in the position shown utterly irrespective of any change-which may take place in the motor connections.

W hen it is desired to stop the car, the motorman simply presses the stud O, which, acting through the hell-crank lever N and the link L, causes a partial left-handed rotation' of the arm F. This rotates the shaft H and allows the stops ]L3 h to separate. The spring D is then able to apply the brakes. It will be seen that it is possible in this way to apply the brakes suddenly to their full extent or it is possible to release the spring D only by a certain small amount, as preferred.

The brakes once set will remain in position as long as desired; but the moment that the controller is moved to start the car the solenoid B is immediately energized and attracts its armature D in such a way as to produce a positive disengagement or release of the At the saine time energy is restored by the compression of the spring D suflicient to operate the brakes when it again becomes This device provides, therefore, means for positively disengaging the brakeshoes at the time of starting the car depend ent upon and actuated by the current in the motor-circuit, such means acting also in the arrangement illustrated as a part of the necessary controlling resistance and being ordinaril y cut out after it has performed its oflice. By the positive disengagement or release of the brakeshoes I mean a power-actuated release positively overcoming frictional or other accidental obstacles. With it I combine auxiliary means for retaining the brake-shoes in their retracted position, and this is by preference under the control of the motorman, and also an automatic device for applying the brakes under control of. but not dependent upon, hand-power. It will be apparent that as the wedge D is maintained by the spring D in contact with the nuts [b3 it, operated by the Worms It If, the spring D is so far under the control of the detent for the brake-releasing mechanism that its force may be utilized to apply the brakes to any desired degree. As the stud O is pressed down, if it be pressed lightly, for instance, the spring will barely cause the engagement of the shoe with thewheel, so as to have but slight retarding effect, while if the stud be pushed down so that the worms are rotated sufficiently far the wedge D will be released altogether and the spring will act to apply the brake-shoes with any desired force, according to its strength. One object of keeping the detent for the brake-shoes under direct control of the motorman is to prevent the automatic application of the brakes when the retracting device is cut out, which otherwise would occur. The objects of the invention, it is manifest, could be carried out by other mechanism or connections than those shown; but I aim to include all such variations in the 20. The combination of a motor to be regulated, a resistance, a counter-electromotive device, means for storing mechanical energy derived from said counter-electromotive-force device, and a switch for connecting the resistance, the counter-electrbmotive-force device and the motor in circuit and for cutting the resistance out of circuit step by step and dis simultaneously cutting the counter-electromotive-force deviceout of circuit. 10

In Witness whereof I have hereunto set my hand this 13th day of April, 1898.

FRANK E. CASE.

Witnesses: I

B. B. HULL, C. L. HAYNES. 

